Rifle Headspace

[444]

I am a great lover of milsurp rifles. I probably own 20 or so 50+ year old milsurp rifles from all over the world. Some were pristine, others looked like they had been there and back. Some have serial numbers on every part, some don't. None were ever checked by me for headspace. I have fired almost all of them with full power service ammo with no problem.
I recently aquired two new ones. One is a 1917 Eddystone and the other is an M1 Carbine. The 1917 has a bolt, but some time in years past it had rusted. The knob is heavily pitted and the top of the bolt face was rusted and is heavily pitted (other than the bolt, the rifle is VERY nice. It isn't museum quality, but very nice). The bolt has a serial number on it that doesn't match the rifle. My research into the 1917 says that bolts were not engraved with serial numbers by the US and if you have one with a serial number, it was put there by another country in a Lend Lease type deal. New bolts are cheap. I bought one.
The M1 Carbine is something I bought from one of our members here. He had one of the locking lugs shear off while firing it. I bought it from him with the full understanding that a problem may exist and I shouldn't fire it without getting it examined by a gunsmith. However, while waiting on it to arrive I purchased not one, but two bolts.
Now comes the problem. What about headspace ? I don't own any headspace gauges. The cost of headspace gauges is about $30 each. I don't know enough about the issue to know if I need a go, no-go, and field but if I do, that is ninety bucks and if it isn't within tolorance I have to get it fixed on top of that. Not a very attractive proposition for an old milsurp, even as much as I love them.
So how critical is headspace ? How many of these old rifles do you think would be within spec if they were tested (all the milsurp rifles floating around today) ? Do you think that units operating in the field bothered to check headspace when they replaced parts ? Articles like this:http://www.jouster.com/trivia/bravemen.htm make me wonder. I would think that military rifles, even the old 1917s and 1903s were mass produced. I would think that the parts were produced to standard dimensions within certain tolorances. It would seem to me that the parts could be interchanged in most cases. What do you think the chances are that a lot of these milsurps we buy today were put together from random parts at some time in the past ?
In todays society no one wants to go out on a limb and suggest that someone else do something that may be unsafe, but what do you think the chances are that I could go out and fire these guns and never have a problem ? What do you think the worst case senario would be ? I mean, how severely out of spec could the parts be ? and if they were that bad what would actually happen when fired ? Let's say I fire them and they function OK but are not within spec. can I tell this from looking at the fired case ?

 

[stans]

Headspacing is very important! Too little and the cartridge will be jammed into the chamber and will not have proper expansion space, pressures will be excessively high.

Too much and the cartridge will over expand, leading to split case necks, split or ruptured case bodies, primers pushed out and hot gases cutting and eroding the chamber and action.

I would suggest taking these rifles to a qualified gunsmith and let him fit the bolts and get the headspace correct. You think it is expensive to pay a good gunsmith to do this? Check out how much a trip to the emergency room to get metal fragment removed from various parts of your body will cost. With firearms it is always safety first.

 

[aguyindallas]

444:

I am with you on this one. I have a couple Milsurp items (as you already know since we worked out a deal on the stock) and have the same question. I have an unissued Russiam M44 that I picked up about 4 years ago. Pristine condition. I have fired about 200 rounds out of it. I never had it headspace checked. It will occasionally very slightly split the neck of one of the old Czech rounds, nothing big. I mean, its not busting them wide open or anything. Well, I just received yesterday, another M44. Obvisouly it was an issued weapon as it has its scars. Good parts in my opinion, locks up nice and all. I have that same...what are the chances question as you do.

 

[HSMITH]

You CAN buy the 'go' gauge and use shims to make it longer progressively and determine the length of the chamber. It is NOT the preferred method but it does work. The trick is finding out how long is too long.

Milsurps are often worth less than the headspace gauges but you will be able to sell them when you are done if you buy them.

 

[Jim Watson]

Read Chapter 10 of Hatcher's Notebook for discussion of headspace. Then, if your anxiety is not relieved, get a No-go gauge if you plan to reload the brass, a Field if you don't. You don't need a Go gauge, the rifles will chamber the ammo or they won't (Highly unlikely.)

I read a lot of calls here for headspace checks, I have seen no accounts of blown up guns due to excess headspace.

 

[aguyindallas]

Jim...thank you for the clarification...I am sure that 444 feels the same way!

 

[Clark]

I have 40 ~ 60 surplus rifles.
I have never worried about the heaspace of any of them.

I have had trouble with a .308 Savage 99 sporting rifle.
My father paid for it in the 60's.
My little brother shot flares or something and rotted out the barrel.
He sold the 99 to a friend, who took it for rebarreling to a guy who advertises as "The best gunmsith in Western Washington"
Anyway, when I bought the rifle back from my brother's friend, I chambered a .308 case with 2 layers of masking tape on the case head. It went in. I worked all the way to 5 layers. That is .025" of excess headspace.
So I called up the guy I bought it from, and it turns out, he has never fired it.
He offered to take it back to the gunsmith and get it fixed.
I said, "That guy is never touching that rifle again."
The shoulder had to be moved, and to get the open sights to line up, the shoulder had to be moved a whole thread, and the extractor relief cuts had to be made deeper.
Now it is tight with one layer of masking tape on a .308 case.

 

[444]

I am not trying to be cavilier about this. I also don't want to do anything unsafe. But at the same time, I hesitate to buy tools that I will only use once.
I am mainly just looking for some people's thoughts about headspace in old milsurp rifles.
They were mass produced and I don't really know how throughly each one was tested before putting it out to the troops. I also am quite sure that a lot of these rifles we buy today were just randomly put together from parts lying around. I am also quite sure that in the field repairs of rifles was made with no regard to checking headspace. I am also pretty sure that with the millions of these rifles that were issued, that some GI somewhere put someone else's bolt in his rifle and it happened more than once.

For what it is worth, I took the carbine out and fired it. It seemed to function fine and the cases looked fine also. This of course doesn't ease my mind completely and it may not be optimal, but it works. I am probably going to go ahead and get the headspace checked most likely by me buying a set of headspace gauges in .30 Carbine. With the .30-06 I am not going to try it without checking it first. That is a lot more pressure than the .30 Carbine. Also, I am sure that someone locally has a set of .30-06 headspace gauges that I can use.

 

[444]

It looks like I might be able to rent the gauges here: http://www.reamerrentals.com/directory.htm if I am willing to wait until July 6th.

 

[JNewell]

There is no one-size-fits-all simple answer here.

I do want to make the point that there have been known cases of less than minimum headspace, and that this condition is more likely to be disasterously dangerous than excess headspace. Excess headspace typically involves case separation or other issues that vent gas out the breach where you are at the mercy of the rifle's design and gas-handling ability. Most rifles are at least OK there, though you could get a face full of hot gas, or have the magazine blown out in your hands.

Sub-min HS, however, is more likely to simply blow the rifle up (if it does anything). A milsurp rifle that hasn't been effed with isn't likely to have submin HS, but IIRC there were some 1903 rifles that went through CMP that had come to them with less than min HS from a foreign military organization, so it is possible.

I agree that I hate to buy tools that only get used once...but I also hate to shoot a rifle that will only go bang once.

 

[ClarkEMyers]

Not just Mil-Surp

I have had one high dollar European rifle in .30-'06 whose fired cases would not chamber in other rifles. The old bent paperclip feeler implied an expansion groove so I sectioned a couple cases. I saved the sectioned cases as examples of a near head separation and sent the rifle back to the maker's representative - got it back with a nice new chamber in a nice new barrel. I suspect the original was a low number run in a new setup for those odd Americans and their odd caliber and somebody ran a reamer too deep without further check; maybe somebody had a reamer for the improved cartridge.

I might or might not try firing a firearm I was dubious about in some manner I considered safe - as chamber a dummy, chamber a cartridge with no firing pin, chamber a cartridge with the firearm tied to a spare tire with a string on the trigger - then dimension the fired case.

Obviously not recommending this but I might in some cases go this way myself.

I might even handload long OAL to headspace on the bullet to fireform for a long chamber with due attention and concern for others who might not recognize a long chamber.